package java_mysql;
import java.sql.*;
 
public class main{
   // JDBC driver name and database URL
   static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";  
   static final String DB_URL = "jdbc:mysql://127.0.0.1/school";
 
   //  Database credentials
   static final String USER = "root";
   static final String PASS = "appleyuchi";
 
   public static void main(String[] args) {
   Connection conn = null;
   Statement stmt = null;
   try{
      //STEP 2: Register JDBC driver
      Class.forName("com.mysql.jdbc.Driver");
 
      //STEP 3: Open a connection
      System.out.println("Connecting to a selected database...");
      conn = DriverManager.getConnection(DB_URL, USER, PASS);
      System.out.println("Connected database successfully...");
 
      //STEP 4: Execute a query
//---------------------------下面是增操作----------------------------------------------------------- 
      
 
      stmt = conn.createStatement();
//
//      String sql = "INSERT INTO students (name,sex,age)" +
//                   "VALUES ('Ender','male',8)";
//      stmt.executeUpdate(sql);
//      sql = "INSERT INTO students (name,sex,age)" +
//                   "VALUES ('Bean','male',7)";
//      stmt.executeUpdate(sql);
//      sql = "INSERT INTO students (name,sex,age)" +
//                   "VALUES ('Petra', 'Fema',9)";
//      stmt.executeUpdate(sql);
//      sql = "INSERT INTO students (name,sex,age)" +
//                   "VALUES('God','fema',232)";
//      stmt.executeUpdate(sql);
//      System.out.println("Inserted records into the table...");
      
      
//---------------------------下面是删操作-------------------------------------------
//      String name="Petra";
//      String sql = "delete from students where Name='" + name + "'";
//      stmt.executeUpdate(sql);
      
//---------------------------下面是改操作-------------------------------------------    
//      int age=78;
//      String name="God";
//      String sql = "update students set Age='" + age + "' where Name='" + name + "'";
//      stmt.executeUpdate(sql);
      
//---------------------------下面是查操作-------------------------------------------      
      
      int age=8;
      
        String sql="select * from students where age='"+age+"'";
            ResultSet rs=stmt.executeQuery(sql);//执行查询该表
            while(rs.next())
            {
                int id=rs.getInt(1);
                String name=rs.getString(2);
                String sex=rs.getString(3);
                System.out.println(id+","+name+","+sex);
            }
 
      
 
      
      
      
 
   }catch(SQLException se){
      //Handle errors for JDBC
      se.printStackTrace();
   }catch(Exception e){
      //Handle errors for Class.forName
      e.printStackTrace();
   }finally{
      //finally block used to close resources
      try{
         if(stmt!=null)
            conn.close();
      }catch(SQLException se){
      }// do nothing
      try{
         if(conn!=null)
            conn.close();
      }catch(SQLException se){
         se.printStackTrace();
      }//end finally try
   }//end try
   System.out.println("Goodbye!");
}//end main
}//end JDBCExampl